In the production process of thin film transistor-liquid crystal displays (TFT-LCDs), it is inevitable to generate numerous defective display panels (for example, with moiré or abnormal pixel points). To reduce defective rate, improve yield rate and reduce loss, engineers need to analyze positions where defects occur on display panels, and usually need to sample and analyze defects. During sampling, engineers need to determine positions where the defects occur at first and then mark the positions.
Specifically, an engineer observes a display panel through a microscope, find a position where a defect occurs on the display panel and then manually marks the position with a marker pen.
However, in the process of manually marking the positions where the defects occur on the display panels to be marked with marker pens, it is found that the accuracy of marking cannot be specifically corrected to a pixel due to too large range of manual marking, and meanwhile, marking is made inconveniently because approximate locations where the defects occur need to be determined with naked eyes through microscopic lens during marking.